Genital herpes virus infection is caused by infection of male or female genital tissues by herpes simplex virus type 2 (HSV-2) or less frequently by herpes simplex virus type 1 (HSV-1). This proposal will focus on HSV-2. Infection in the female can target the labial surfaces, the vagina and the cervix. Adjacent areas of buttock skin also may be infected. Infection may occur as a primary event, usually as a result of sexual transmission. Following primary infection, virus most often enters latency in sacral ganglia and can serve as a source of recurrent infection. Primary infection is usually more severe, but recurrent infections may occur over a number of years and serve as a potent source of transmittable virus. Incidence of this virus infection is extremely high. Immunosuppressed patients are at grave risk for replication of this virus at all tissues and can suffer life-threatening sequelae. The current mainstay of therapy for HSV- 2 infection is Acyclovir, a potent nucleotide analogue specifically phosphorylated and incorporated into DNA in HSV-infected cells. Intravenous, oral and topical formulations of this compound have therapeutic benefit. In addition, certain detergent based spermicides have proven anti-virucidal activity for HSV. Studies in the previous three years of this Program Project have shown that C31G (C14/C16) and an alkyl sulfate microbicide can each inactivate HSV-2. Importantly, SDS has been shown to prevent HSV-2 infection in an in vivo model of infection in the mouse vaginal and SDS and C31G have been shown to inactivate HSV-2 and prevent infection in a human vaginal xenograft model. Our specific aims in the next phase of this grant will include: 1) continue to employ three model systems for HSV-2 growth to determine the toxicity and efficacy of non-formulated and formulated microbicidal compounds: a) in vitro assay of HSV-2 by plaque formation in monkey kidney epithelial cells and primary human vaginal keratinocytes; b) in vivo assay by vaginal inoculation of Swiss-Webster, outbred mice, c) in vivo assay by inoculation of human, vaginal xenografts growing in immunocompromised mice; 2) compare the kinetics and natural history of HSV-2 infection following inoculation of either normal, human, vaginal xenografts or human vaginal xenografts expressing the complete repertoire of viral genes from HPV-11; and 3) determine if acute of subclinical HSV-2 infection of human vaginal xenografts growing in nude mice, SCID mice or SCID mice that have been reconstituted with human lymphoreticular cells, alters the complexity of cells in the xenografts that serve as potential targets for HIV infection.